PHPCon Poland 2024

PostgreSQL Funzioni



Not all functions are supported by all builds. It depends on your libpq (The PostgreSQL C client library) version and how libpq is compiled. If PHP PostgreSQL extensions are missing, then it is because your libpq version does not support them.


Most PostgreSQL functions accept connection as the optional first parameter. If it is not provided, the last opened connection is used. If it doesn't exist, functions return false.


PostgreSQL automatically folds all identifiers (e.g. table/column names) to lower-case values at object creation time and at query time. To force the use of mixed or upper case identifiers, you must escape the identifier using double quotes ("").


PostgreSQL does not have special commands for fetching database schema information (eg. all the tables in the current database). Instead, there is a standard schema named information_schema in PostgreSQL 7.4 and above containing system views with all the necessary information, in an easily queryable form. See the » PostgreSQL Documentation for full details.

Indice dei contenuti

  • pg_affected_rows — Restituisce il numero delle tuple coinvolte dall'ultimo comando
  • pg_cancel_query — Annulla una query asincrona
  • pg_client_encoding — Restituisce la codifica caratteri del client
  • pg_close — Chiude una connessione PostgreSQL
  • pg_connect_poll — Poll the status of an in-progress asynchronous PostgreSQL connection attempt
  • pg_connect — Stabilisce una connessione PostgreSQL
  • pg_connection_busy — Riferisce se una connessione è occupata o meno
  • pg_connection_reset — Rpristina la connessione (riconnette)
  • pg_connection_status — Restituisce lo stato di una connessione
  • pg_consume_input — Reads input on the connection
  • pg_convert — Converte i valori di un array associativo in una forma compatibile con i comandi SQL.
  • pg_copy_from — Inserisce le tuple in una tabella prendendole da un array
  • pg_copy_to — Copia una tabella in un array
  • pg_dbname — Restituisce il nome del database
  • pg_delete — Cancella le tuple.
  • pg_end_copy — Esegue una sincronizzazione con il backend PostgreSQL
  • pg_escape_bytea — Aggiunge le sequenze di escape ai dati binari nel tipo bytea
  • pg_escape_identifier — Escape a identifier for insertion into a text field
  • pg_escape_literal — Escape a literal for insertion into a text field
  • pg_escape_string — Aggiunge le sequenze di escape nei tipi text/char
  • pg_execute — Sends a request to execute a prepared statement with given parameters, and waits for the result
  • pg_fetch_all_columns — Fetches all rows in a particular result column as an array
  • pg_fetch_all — Carica tutte le tuple in un array
  • pg_fetch_array — Carica una tupla in un array
  • pg_fetch_assoc — Recupera una riga come array associativo
  • pg_fetch_object — Carica una tupla in un oggetto
  • pg_fetch_result — Restituisce i valori da una risorsa di risultato
  • pg_fetch_row — Carica una tupla in un array
  • pg_field_is_null — Verifica se un campo è null
  • pg_field_name — Restituisce il nome di un campo
  • pg_field_num — Restituisce la posizione del campo specificato
  • pg_field_prtlen — Restituisce la lunghezza "stampabile" di un valore
  • pg_field_size — Restituisce la reale dimensione di memorizzazione del campo
  • pg_field_table — Returns the name or oid of the tables field
  • pg_field_type_oid — Returns the type ID (OID) for the corresponding field number
  • pg_field_type — Restituisce il nome del tipo del campo specificato
  • pg_flush — Flush outbound query data on the connection
  • pg_free_result — Libera la memoria allocata per i risultati
  • pg_get_notify — Ottiene il messaggio SQL NOTIFY
  • pg_get_pid — Ottiene l'ID del processo del backend
  • pg_get_result — Recupera i risultati di una query asincrona
  • pg_host — Restituisce il nome dell'host associato alla connessione
  • pg_insert — Inserisce un array in una tabella.
  • pg_last_error — Restituisce l'ultimo messaggio d'errore di una connessione
  • pg_last_notice — Restituisce l'ultimo messaggio di notifica dal server PostgreSQL
  • pg_last_oid — Restituisce l'oid dell'ultimo oggetto
  • pg_lo_close — Chiude un large object
  • pg_lo_create — Crea un large object
  • pg_lo_export — Esporta un large object salvandolo su un file
  • pg_lo_import — Importa un large object da un file
  • pg_lo_open — Apre un large object
  • pg_lo_read_all — Legge interamente un large object e lo manda direttamente al browser
  • pg_lo_read — Legge un large object
  • pg_lo_seek — Ricerca la posizione di un large object
  • pg_lo_tell — Restituisce la posizione attuale in un large object
  • pg_lo_truncate — Truncates a large object
  • pg_lo_unlink — Cancella un large object
  • pg_lo_write — Scrive un large object
  • pg_meta_data — Ottiene la definizione di una tabella.
  • pg_num_fields — Restituisce il numero di campi
  • pg_num_rows — Restituiscein numero di tuple
  • pg_options — Estrae le opzioni associate alla connessione
  • pg_parameter_status — Looks up a current parameter setting of the server
  • pg_pconnect — Open a persistent PostgreSQL connection
  • pg_ping — Effettua il ping alla connessione del database
  • pg_port — Restituisce il numero di porta associato alla connessione
  • pg_prepare — Submits a request to create a prepared statement with the given parameters, and waits for completion
  • pg_put_line — Invia una stringa terminata da NULL al backend PostgreSQL
  • pg_query_params — Submits a command to the server and waits for the result, with the ability to pass parameters separately from the SQL command text
  • pg_query — Esegue una query
  • pg_result_error_field — Returns an individual field of an error report
  • pg_result_error — Restituisce i messaggio di errore associato al risultato
  • pg_result_seek — Imposta l'offset di riga interno nella risorsa risultato
  • pg_result_status — Recupera lo stato del risultato di una query
  • pg_select — Seleziona delle tuple.
  • pg_send_execute — Sends a request to execute a prepared statement with given parameters, without waiting for the result(s)
  • pg_send_prepare — Sends a request to create a prepared statement with the given parameters, without waiting for completion
  • pg_send_query_params — Submits a command and separate parameters to the server without waiting for the result(s)
  • pg_send_query — Invia una query in modo asincrono
  • pg_set_client_encoding — Imposta la codifica del client
  • pg_set_error_context_visibility — Determines the visibility of the context's error messages returned by pg_last_error and pg_result_error
  • pg_set_error_verbosity — Determines the verbosity of messages returned by pg_last_error and pg_result_error
  • pg_socket — Get a read only handle to the socket underlying a PostgreSQL connection
  • pg_trace — iAbilita il tracciamento di una connessione PostgreSQL
  • pg_transaction_status — Returns the current in-transaction status of the server
  • pg_tty — Restituisce il nome della tty associata alla connessione
  • pg_unescape_bytea — Rimuove i caratteri di escape in modo binario per il tipo bytea
  • pg_untrace — Disabilita il tracciamento di una connessione PostgreSQL
  • pg_update — Modifica le tuple della tabella
  • pg_version — Returns an array with client, protocol and server version (when available)
add a note

User Contributed Notes 18 notes

Tony Murray
12 years ago
A simple conversion for 1D PostgreSQL array data:

// =====
//Example #1 (An array of IP addresses):
= '{,}';

preg_match('/^{(.*)}$/', $pgsqlArr, $matches);
$phpArr = str_getcsv($matches[1]);

// Output:
// Array
// (
// [0] =>
// [1] =>
// )
// =====

// =====
// Example #2 (An array of strings including spaces and commas):
= '{string1,string2,"string,3","string 4"}';

preg_match('/^{(.*)}$/', $pgsqlArr, $matches);
$phpArr = str_getcsv($matches[1]);

// Output:
// Array
// (
// [0] => string1
// [1] => string2
// [2] => string,3
// [3] => string 4
// )
// =====
abondi at ijk dot it
20 years ago
I've found another function to mimic the following mysql list tables function ( that's more useful for my target:

function pg_list_tables() {
$sql = "SELECT a.relname AS Name
FROM pg_class a, pg_user b
WHERE ( relkind = 'r') and relname !~ '^pg_' AND relname !~ '^sql_'
AND relname !~ '^xin[vx][0-9]+' AND b.usesysid = a.relowner
AND NOT (EXISTS (SELECT viewname FROM pg_views WHERE viewname=a.relname));";
return(pg_query($conn, $sql));
1413 at blargh dot com
18 years ago
Here is some quick and dirty code to convert Postgres-returned arrays into PHP arrays. There's probably a billion bugs, but since I'm only dealing with variable-depth-and-length arrays of integers, it works for my needs.

Most notably, any data that might have commas in it won't work right...

function PGArrayToPHPArray($pgArray)
$ret = array();
$stack = array(&$ret);
$pgArray = substr($pgArray, 1, -1);
$pgElements = explode(",", $pgArray);


$pgElements as $elem)
substr($elem,-1) == "}")
$elem = substr($elem,0,-1);
$newSub = array();
substr($elem,0,1) != "{")
$newSub[] = $elem;
$elem = array_pop($ret);
$newSub[] = substr($elem,1);
$ret[] = array_reverse($newSub);
$ret[] = $elem;
74012 dot 2773 at compuserve dot com
19 years ago
for just a list of tables, this works with postgresql-7.2.1:

function pg_list_tables($db) {
$sql = "select relname from pg_stat_user_tables order by relname;";
return pg_query($db, $sql);
daniel at bichara dot com dot br
21 years ago
Running RedHat Linux and Apache with suexec enabled you must include on each .php file using dl("") and remove "" from php.ini, otherwise Apache (httpd) will not start.
saberit at home dot com
22 years ago
I tried compiling PHP from source with PostgreSQL support (./configure --with-pgsql=/usr/local/pgsql) and ran into a bunch of problems when trying to 'make'. The problem was that some of the PostgreSQL headers were not installed by default when I installed PostgreSQL from source. When installing PostgreSQL make sure you 'make install-all-headers' after you 'make install'.
WillowCatkin at hotmail dot com
19 years ago
There is an example:
* Define PostgreSQL database server connect parameters.
define('PGUSER', 'root');
define('PGPASSWORD', 'nopass');
define('ERROR_ON_CONNECT_FAILED','Sorry, can not connect the database server now!');

* Merge connect string and connect db server with default parameters.
pg_pconnect('host=' . PGHOST . ' port=' . PGPORT . ' dbname=' . PGDATABASE . ' user=' . PGUSER . ' password=' . PGPASSWORD);

* generate sql statements to call db-server-side stored procedure(or function)
* @parameter string $proc stored procedure name.
* @parameter array $paras parameters, 2 dimensions array.
* @return string $sql = 'select "proc"(para1,para2,para3);'
* @example pg_prepare('userExists',
* array(
* array('userName','chin','string'),
* array('userId','7777','numeric')
* )
* )
function pg_prepare($proc, $paras)
$sql = 'select "' . $proc . '"(';
$sql .= $paras[0][2] == 'numeric' ? $paras[0][1] : "'" . str_replace("'","''",$paras[0][1]) . "'";
$len = count($paras);
for (
$i = 1; $i < $len; $i ++)
$sql .= ',';
$sql .= $paras[$i][2] == 'numeric' ? $paras[$i][1] : "'" . str_replace("'","''",$paras[$i][1]) . "'";
$sql .= ');';
17 years ago
Lots of advice on stored procedures didn't work for me. This did:

= pg_query( $connection, "BEGIN; DECLARE s CURSOR FOR SELECT get_consumer('harry'); FETCH ALL IN s; END;" );

..where harry looks like this:

CREATE OR REPLACE FUNCTION get_consumer( varchar )
RETURNS refcursor
AS '
_name ALIAS FOR $1;
r refcursor;
OPEN r FOR SELECT name FROM consumer
WHERE = _name
' LANGUAGE 'plpgsql';
anonymous at unknown dot com
21 years ago
I just wanted to add to my previous post I've got the system up and running.
Environment: Windows XP, Apache 1.3.23, Php 4.3 RC2, PostGreSQL beta4 native windows build

Installation was fairly easy:
1. read the readme.txt
2. edit the setenv.bat as described in readme
3. run 'initdb'
all execs are in /bin
help is accessed like <command> --help
4. Start the psql deamon - you may want to create a batch file like
'D:\postgres_beta4\bin\postmaster -h localhost -D D:/postgres_beta4/data'

--deamon should be up and running now--

You can login into a shell from a console like
'psql -h localhost -d <username>'

You must load the postgresql extension by editing the php.ini and restarting apache in order to access psql with php.

And one final not: when running
$dbconn = pg_connect ("host=localhost port=5432 dbname=$dbname user=$user");
remember that $user and or $dbname is CASESENSITIVE.

Oh yeah, I created the data dir manually - don't know whether that was necessary

Grtz Vargo
anis_wn at gawab dot com
19 years ago
Setting up PostgreSQL for higher security PHP connection.

We want to connect to PostgreSQL database using username and password supplied by webuser at login time.

Fact (Linux):
Apache (perhaps other servers, too) running the server as (default to) apache user account. So if you connect to PostgreSQL using default user, apache will be assingned for it. If you hard code the user and password in your PHP script, you'll loose security restriction from PostgreSQL.

(You are assumed to have enough privilege to do these things, though)
1. Edit pg_hba.conf to have the line like the one below
host db_Name [web_server_ip_address] [ip_address_mask] md5
2. Add to you script the login page that submits username and password.
3. Use those information to login to PostgreSQL like these...
$conn = "host=$DBHost port=$DBPort dbname=$DBName ".
"user='{$_POST['dbUsername']}' password='{$_POST['dbPassword']}'";
$db = pg_connect ($conn);
[your other codes go here...]
4. You must add users in PostgreSQL properly.
5. For your convenience, you can store the username and password to $_SESSION variable.

Good luck.
Anis WN
mystran at wasteland dot pp dot htv dot fi
22 years ago
Nice to know fact that I didn't find documented here.

PHP will return values of PostgreSQL boolean datatype as single character strings "t" and "f", not PHP true and false.

[Editor's Note]
't' or 'f' is valid boolean expression for PostgreSQL.

All values from PostgreSQL are strings, since PostgreSQL integer, float may be much larger than PHP's native int, double can handle. PostgreSQL array is not supported.
passion at monkey dot org
22 years ago
I've tried to mimic the following mysql database connection functions for postgres.

These are assuming that you're passing in $link as the result from pg_connect:

function pg_list_dbs($link)
$sql = 'SELECT datname FROM pg_database';
return (pg_query($link, $sql));

function pg_list_tables($link)
$sql = "SELECT relname FROM pg_class WHERE relname !~ '^pg_'";
return (pg_query($link, $sql));
adaml at mimuw edu pl
19 years ago
Yes, PHP does support stored procedures
You have to add "select" before the name of the
procedure, just like that:

$result = pg_querry($conn, "SELECT procedure_x($aa)");

if a procedure returns a cursor you do something like that:

$result = pg_query($conn, "SELECT procedure_x('rcursor'); FETCH ALL IN rcursor");
hubert at hubertmuller dot com
22 years ago
The best way to find the separated list of tables, sequences, keys etc is:

SELECT relname FROM pg_class WHERE relkind='<value>' AND relname !~ '^pg_';

<value> takes:
i for keys,
r for relations,
S for sequences

Note that all tables names that begins with 'pg_' are PostgreSQL internal tables (this explain why I use AND relname !~ '^pg_' condition).
!spamcraig at ahdore dot com
23 years ago
If you want to extract data from select statements, you need to store the result index, and then apply pg_result to that value. Basically, do this

$resultIdx = pg_query ($database, "select * from tablename");
$mySelect = pg_fetch_result($resultIdx, 0, 0); // gets column 0 of tuple 0
echo("My select: [".$mySelect."]");

I'm new to php and had to do some fiddling around to work this out. It's reasonably elementary, but not demonstrated by the examples on these pages. Hopefully it will come in useful to someone else.
bleach at chek dot com
24 years ago
If you want to see all the objects in a database, you can find that information in the pg_class table. <BR>
SELECT * FROM pg_class;<BR>
Now this is going to be kind of long and complex, to see how psql command handles the \d and other things. use the syntax. psql -E <Database>, ie psql -E mydatabase <BR>
What this will do is show the SQL command used for everything. So when you type a \d or something, it shows the SQL query used for the result.
Chris KL
18 years ago
Here is a better array parser for PHP. It will work with 1-d arrays only. Unlike the example below it will work in all cases.

* Change a db array into a PHP array
* @param $arr String representing the DB array
* @return A PHP array
function phpArray($dbarr) {
// Take off the first and last characters (the braces)
$arr = substr($dbarr, 1, strlen($dbarr) - 2);

// Pick out array entries by carefully parsing. This is necessary in order
// to cope with double quotes and commas, etc.
$elements = array();
$i = $j = 0;
$in_quotes = false;
while ($i < strlen($arr)) {
// If current char is a double quote and it's not escaped, then
// enter quoted bit
$char = substr($arr, $i, 1);
if ($char == '"' && ($i == 0 || substr($arr, $i - 1, 1) != '\\'))
$in_quotes = !$in_quotes;
elseif ($char == ',' && !$in_quotes) {
// Add text so far to the array
$elements[] = substr($arr, $j, $i - $j);
$j = $i + 1;
// Add final text to the array
$elements[] = substr($arr, $j);

// Do one further loop over the elements array to remote double quoting
// and escaping of double quotes and backslashes
for ($i = 0; $i < sizeof($elements); $i++) {
$v = $elements[$i];
if (strpos($v, '"') === 0) {
$v = substr($v, 1, strlen($v) - 2);
$v = str_replace('\\"', '"', $v);
$v = str_replace('\\\\', '\\', $v);
$elements[$i] = $v;

return $elements;
17 years ago
Chris KL: Will parse well {"\\"}? The second " will be treat as escaped while it shoudn't...
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